[Ffmpeg-devel] Partial frame decode in avcodec?

[Måns Rullgård]

"Matt Schuckmann" <mschuck at imoveinc.com> writes:

>> What happens if a predicted block depends on pixels outside the
>> region?  Are you sure your old decoder didn't simply decode the full
>> frame and crop it for you?
>
> I don't know about the predictive block question I haven't looked into it to
> closely. I'm kind of new to video compression but maybe the fact that the
> old codec doesn't use P frames has something to do with it or maybe it goes
> back and decodes just those blocks in needs. 

What is this old codec really?  I thought you said it was an mpeg4
implementation, but maybe I misunderstood you.

> I'm certain the old codec only decodes the specified region (or something
> close to it) because testing shows that if I have it decode only 1/4 of the
> frame the processing time drops by about 75%. 

That sounds rather convincing.

-- 
M?ns Rullg?rd
mru at inprovide.com